title: Characterization of damaged skin by impedance spectroscopy: chemical damage by dimethyl sulfoxide.
abstract: OBJECTIVE
  To relate changes in the electrochemical impedance spectra to the progression and mechanism of skin damage arising from exposure to dimethyl sulfoxide (DMSO).
  
  
  METHODS
  Electrochemical impedance spectra measured before and after human cadaver skin was treated with neat DMSO or phosphate buffered saline (control) for 1 h or less were compared with electrical circuit models representing two contrasting theories describing the progression of DMSO damage. Flux of a model lipophilic compound (p-chloronitrobenzene) was also measured.
  
  
  RESULTS
  The impedance spectra collected before and after 1 h treatment with DMSO were consistent with a single circuit model; whereas, the spectra collected after DMSO exposure for 0.25 h were consistent with the model circuits observed before and after DMSO treatment for 1 h combined in series. DMSO treatments did not significantly change the flux of p-chloronitrobenzene compared to control.
  
  
  CONCLUSIONS
  Impedance measurements of human skin exposed to DMSO for less than about 0.5 h were consistent with the presence of two layers: one damaged irreversibly and one unchanged. The thickness of the damaged layer increased proportional to the square-root of treatment time until about 0.5 h, when DMSO affected the entire stratum corneum. Irreversible DMSO damage altered the lipophilic permeation pathway minimally.
authors.affiliation: Chemical and Biological Engineering Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, USA.
authors.forename: Erick A
authors.initials: EA
authors.lastname: White
authors.forename: Mark E
authors.initials: ME
authors.lastname: Orazem
authors.forename: Annette L
authors.initials: AL
authors.lastname: Bunge
mesh_terms: D000368:Aged; D002102:Cadaver; D058266:Dielectric Spectroscopy / Q000295:instrumentation / Q000379:methods*; D015194:Diffusion Chambers, Culture; D004121:Dimethyl Sulfoxide / Q000737:chemistry / Q000633:toxicity*; D017097:Electric Impedance; D006801:Humans; D008297:Male; D008954:Models, Biological; D009578:Nitrobenzenes / Q000493:pharmacokinetics; D010539:Permeability; D010636:Phenols / Q000493:pharmacokinetics; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D012997:Solvents / Q000737:chemistry / Q000633:toxicity*
chemical_list: D009578:Nitrobenzenes; D010636:Phenols; D012997:Solvents; C007178:4-cyanophenol; C010407:4-chloronitrobenzene; D004121:Dimethyl Sulfoxide